text: It is produced in eukaryotic organisms from succinate in complex 2 of the electron transport chain via the enzyme succinate dehydrogenase. 
  Fumaric acid is found in fumitory (Fumaria officinalis), bolete mushrooms (specifically Boletus fomentarius var. pseudo-igniarius), lichen, and Iceland moss.
  Fumarate is an intermediate in the citric acid cycle used by cells to produce energy in the form of adenosine triphosphate (ATP) from food.  It is formed by the oxidation of succinate by the enzyme succinate dehydrogenase.  Fumarate is then converted by the enzyme fumarase to malate.
  Human skin naturally produces fumaric acid when exposed to sunlight.
  Fumarate is also a product of the urea cycle.